Assessment of rhizosphere processes for removing water-borne macrolide antibiotics in constructed wetlands
Limited information is available on plant rhizosphere processes for removing antibiotics in antibiotic-contaminated waters. This study identifies rhizosphere processes and evaluates their relative contributions for the macrolides (ML) removal in aquatic plant systems.
A flask-scale experiment (100 and 300 μg/L ML) incorporating Juncus effuses and Canna indica was used to identify the root adsorption, rhizobacterial influences, and plant uptake responsible for the ML (i.e., anhydroerythromycin A, roxithromycin, clarithromycin and tilmicosin) removal.
Total ML removal rates due to rhizosphere processes were respectively 43.7–67.6% and 44.3–82.2% at 100 and 300 μg/L ML. J. effuses removed ML more effectively than C. indica (P < 0.05). The relative contribution of rhizospheric pathways to remove all ML followed the order: root sorption > rhizobacterial influence > plant uptake (P < 0.01). Sorption and rhizobacterial activity were important removal pathways in wetland plant microcosms, accounting for 36.5–72.8% and 20.5–54.2% of the total rhizosphere associated removal of ML, respectively.
Root sorption and rhizobacterial influence were the main rhizospheric pathways of ML removal in aquatic plant systems. Fe plaque on the root surface, rhizobacterial number and bacterial activity play significant roles in the removal of target pollutants.
KeywordsMacrolides Aquatic plant system Rhizospheric pathway Root sorption Rhizobacterial activity
We are also grateful to the National Natural Science Foundation of China (51509106, 51579115), the National Science Foundation for Post-doctoral Scientists of China (2015 M572410), the Natural Science Foundation of Guangdong Province (2016A030310097), and Pearl River S&T Nova Program of Guangzhou (201710010052), China for financial support.
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